Latino adolescents, especially those living in Puerto Rico, are at high risk for HIV/AIDS, other sexually transmitted infections (STIs), and unintended pregnancies. A web-based parent communication intervention provides an opportunity to benefit adolescents by providing additional support for safer sex decisions, and to increase parents' involvement in sexual health by decreasing barriers that keep them from participating in these interventions. The purpose of this proposed study is to evaluate a brief, theoretically informed, culturally appropriate, and linguistically tailored web-based parental communication program, Cudalos (Take care of them), designed to improve parent-adolescent sexual communication and reduce adolescent sexual risk behavior. Recent findings from an R21 RCT testing a brief computer-based version of the Cudalos program indicated that the program increased parent-adolescent general communication and sexual risk communication with English and Spanish speaking U.S. Latinos.7 In this proposed study, we plan to modify the Cudalos intervention by changing to a web-based format, increasing the amount of content related to sexual communication and adding a module on HIV/AIDS stigma. In this RCT, we will recruit parents (n=680) and one of their adolescents (n=680) from community-based agencies in Puerto Rico, and will be randomly assigned to receive either the parent-based Cudalos intervention or a web-based health promotion control condition. Parents and adolescents will complete measures at pre-intervention and at 3-(parents only), 6-, and 12-month follow-ups. We will address the five following specific aims: 1) Does the Cudalos intervention increase parents' comfort with, as well as the amount of, communication with adolescents and decrease stigma at 3-,6-, and 12- month follow-ups as compared to the general health promotion control intervention; 2) Does the Cudalos intervention decrease self-reported adolescent intercourse and unprotected intercourse at the follow-ups as compared to the general health promotion control intervention; 3) Do theory-based variables (attitudes, subjective norms, perceived behavioral control, intentions) mediate the intervention effects of Cudalos on parents' communication with their adolescents; 4) Are the effects of the Cudalos intervention on adolescent sexual behavior and parent-adolescent communication moderated by individual (adolescents: sexual experience, gender, age, stigma; parents: gender, age computer access/experience, frequency and time engaged in the program), and microsystem (adolescents: parent-adolescent communication) variables; and 5) Puerto Rican and Latino youth, the lack of culturally and linguistically effectiv interventions for Latino parents and adolescents, and the absence of web-based interventions for Latinos. If the program is efficacious, the web-based format will accelerate the translation of this program into public health practice and will be an important contribution in supporting safe adolescent sexual health behaviors. Is the intervention cost-effective? This study addresses existing disparities in sexual health outcomes among